The present invention relates generally to medical imaging and developing imaging protocols and, more particularly, to a method and apparatus to determine a likelihood of artifact presence in a reconstructed image and displaying the likelihood of artifact presence to an operator for evaluation. The present invention enables redevelopment and/or redesigning of the imaging protocol based upon the likelihood of artifact presence in a reconstructed image.
Typically, helical reconstruction algorithms produce artifacts in a reconstructed image due to data inconsistencies generated by a patient translation in a z direction during gantry rotation. While the intensity of artifacts depends in large part on the particular scanning parameters of the scanning session, generally these artifacts are most intense around high contrast interfaces such as bone/tissue (ribs) or air/tissue cavities. Additionally, artifact intensity typically increases with pitch but may also change depending upon the implemented helical reconstruction algorithm and detector width used to acquire imaging data.
With known imaging systems, it is incumbent upon the scanner operator to understand the artifact intensity with prescribing a patient examination. Typically, the operator learns from experience whether a particular scan procedure will result in an increased or decreased artifact presence. Moreover, the operator must be cognizant of scan versus artifact presence for a number of scanning possibilities without the benefit of any visual queues. While under some circumstances a large artifact presence in the final reconstructed image is not bothersome, for other scan procedures a reconstructed image absent visual artifacts is paramount.
For single slice CT systems that employ simple reconstruction weighting schemes, the scanning operators typically utilize the helical pitch of the scan as an indication of expected artifact. This can be difficult however for a new or inexperienced operator or for a CT system that has numerous operating modes. Furthermore, in multi-slice CT systems, with various pitch and detector width selections, an operator or technologist may find it very difficult to remember what to expect for each set of operating conditions.
Therefore, it would be desirable to design an apparatus and method that determines and visually displays a likelihood of artifact presence in a reconstructed image for evaluation by a scan system operator. Further, it would be desirable to design such a system that enables the system operator to provide feedback to the system such that artifact presence is reduced in a subsequent imaging session.
An apparatus and process overcoming the aforementioned drawbacks is provided and includes determining and displaying a helical artifact index (HAI) to a system operator. The HAI is determined by acquiring and processing imaging data of a phantom. The HAI is then displayed to the operator on a console so that the operator may, if necessary, reset the scanning parameters or select a new scanning protocol that will result in a reconstructed image of a patient having reduced artifact presence. By providing a likelihood of artifact presence to the system operator, the present invention eliminates the need for the operator to recall those scanning profiles that are susceptible to high artifact presence.
Therefore, in accordance with one aspect of the present invention, a method of generating a helical artifact score is provided. The method includes acquiring a set of data values and setting a subset of the set of data values to an initial value. After setting the subset of data values to an initial value, the method includes filtering the set of data values. Next, a likelihood of artifact presence is determined from the filtered set of data values.
In accordance with another aspect of the present invention, a computer-readable medium having stored thereon a computer program that, when executed by one or more computers, causes the one or more computers to acquire imaging data of a phantom from an external device. The imaging data includes a plurality of pixels. The computer program further causes the one or more computers to isolate a first set and a second set of pixels and set one of the first set and the second set to an initial value. After setting one of the first set and the second set to an initial value, the computer program causes the one or more computers to filter the imaging data and determine a helical artifact index (HAI) therefrom. The computer program then causes the one or more computers to visually display the HAI on a console.
In yet another aspect of the present invention, a CT system is provided and comprises a rotatable gantry having an opening and a high frequency electromagnetic energy projection source to project high frequency energy toward an object. The CT system further includes a scintillator array having a plurality of scintillators to receive high frequency electromagnetic energy attenuated by the object. A photodiode array is provided having a plurality of photodiodes. The photodiode array is optically coupled to the scintillator array and is configured to detect light energy emitted therefrom. The CT system further includes a plurality of electrical interconnects configured to transmit photodiode outputs to a data processing system and a computer program to acquire and process data to determine a likelihood of an artifact risk presence in a reconstructed image. The computer of the CT system is further programmed to notify an operator of the determined likelihood.
Various other features, objects and advantages of the present invention will be made apparent from the following detailed description and the drawings.